Foamed compositions and methods of use in subterranean zones

ABSTRACT

The current invention provides improved methods and compositions for completing a well bore. In one aspect, the current invention provides a process for preparing a foamed cement composition. The process utilizes air to foam the cement after the air has been treated to lower the oxygen content below that concentration necessary to support combustion. Additionally, the current invention provides a process for completing a well bore using foamed cement wherein the foam is generated with reduced oxygen content air. Finally, the current invention provides a foamed cement composition wherein the gaseous portion of the composition is air having a reduced oxygen content.

BACKGROUND OF THE INVENTION

The present invention relates to improved well completion methodsutilizing foamed cements and foamed well treatment fluids. Additionally,the present invention provides improved foamed cement and foamed welltreatment fluids and methods for preparing and using the same.

Foamed hydraulic cement compositions are often utilized in cementingsubterranean zones penetrated by well bores. For example, foamed cementcompositions are used in primary well cementing operations wherebystrings of pipe such as casing and liners are cemented in well bores. Aprimary cementing operation normally pumps a cement composition into theannular space between the walls of a well bore and the exterior surfacesof a pipe string disposed therein. The cement composition is permittedto set in the annular space thereby forming an annular sheath ofhardened substantially impermeable cement therein. Thus, the cementsheath physically supports and positions the pipe string in the wellbore and bonds the exterior surfaces of the pipe string to the walls ofthe well bore. In this manner, the cement precludes the undesirablemigration of fluids between zones or formations penetrated by the wellbore.

The geological nature of the formation will dictate the type of cementcomposition appropriate for cementing operations. In order to preventexcessive hydrostatic pressure from unintentionally fracturing theformation, certain formations will require lightweight cement. Toachieve the lower density of a lightweight cement, a foamed cementcomposition contains compressed gas which improves the ability of thecement composition to maintain the pressure necessary to prevent theflow of formation fluid into and through the cement composition duringthe transition time, i.e., the time during which the cement compositionchanges from a true fluid to a hard set mass. Foamed cement compositionsare also advantageous because they have low fluid loss properties due tothe two phases of the system. Therefore, the industry recognizes thebenefits of and frequently uses foamed cement and other foamed fluids insealing casing in subterranean wells.

Although similar to a conventional cementing operation, the process offoaming a cement or wellbore fluid requires additional equipment notcommonly associated with conventional cementing operations. Typically, ahydraulic cement composition is foamed by combining a mixture of foamingand foam stabilizing surfactants with the cement composition on thesurface. Subsequently, as the cement composition is pumped into the wellbore a gas, typically nitrogen, is injected into the cement composition.This process allows the cement composition to have a downhole gasconcentration, or foamed quality, of from about 20% to about 80%, byvolume of the cement composition depending on the downhole pressure andtemperature. This process requires the presence of nitrogen (liquidand/or gas) storage, vaporization, and pumping equipment at the wellsite. Normally equipment of this nature is not used at well sites andmay be unavailable or difficult to transport to remote well sites.Clearly, the use of nitrogen for foaming cement and wellbore fluidscomplicates and adds to the overall burden of foam cementing a wellbore.

In the designing of the foam cement job, prediction software is utilizedto estimate the amount of pressure, if any, required to control theexpansion of the foamed fluids. If excessive expansion is encountered,the gas bubbles will become relatively large and coalesce which willincrease the permeability of the set cement. To accomplish primarycementing with foam cement, it is desirable to have the wellheadequipped with annular pressure-containing devices. Whenpressure-containing devices are not feasible, the preferred practiceruns an unfoamed cement cap ahead of the foamed cement. The unfoamed“cap” interval should be tailored for each specific job. Typically, aninterval of 200-feet is considered the minimum length for the unfoamedcap.

For safety and clean-up ease, the return relief lines are typicallystaked and chained to exit in an acceptable waste area, such as a sumppit. Foamed cement under pressure will expand in volume prolifically ifreleased at atmospheric pressure. This foam is more of a nuisance than aproblem since it develops little strength and can be washed away with apressure hose.

In view of the problems inherent to foaming with nitrogen, it would bedesirable to provide improved foamed cements and foamed well treatmentfluids that do not require nitrogen to generate the foamed cementslurry. Further, considering the inherent risks associated with oxygenin the downhole environment, it would be desirable to provide a foamedcement wherein the foaming gas is air having a reduced oxygen content.

SUMMARY OF THE INVENTION

The current invention provides methods and compositions suitable forovercoming the problems identified with current foamed cementingpractices. In one aspect, the current invention provides a method offoaming cement with air. The method comprises the steps of preparing acement composition comprising hydraulic cement, sufficient water to forma slurry, and a mixture of foaming and foam stabilizing surfactants. Themethod also prepares compressed air with an oxygen content less than anamount necessary to support combustion of hydrocarbons. The compressedair with reduced oxygen content is used to foam the cement composition.

Additionally, the current invention provides a method of foaming cementwith air. The improved method comprises the steps of preparing a cementcomposition comprising hydraulic cement, sufficient water to form aslurry, and a mixture of foaming and foam stabilizing surfactantspresent in an amount sufficient to facilitate the formation andstabilization of foam. The method also prepares compressed air with anoxygen content less than an amount necessary to support combustion ofhydrocarbons by contacting the air with an oxygen scavenger prior to orafter compressing the air. In general, the order of compressing the airand contacting the air with an oxygen scavenger is not critical to thecurrent invention and may be reversed such that the oxygen content islowered by contact with an oxygen scavenger prior to or aftercompressing the air. The reduced oxygen content air is then used to foamthe cement composition.

The current invention further provides an improved method of cementing awell bore penetrating a hydrocarbon producing subterranean zone. Theimproved method comprises the steps of preparing a cement compositioncomprising hydraulic cement, sufficient water to form a slurry, and amixture of foaming and foam stabilizing surfactants. The improved methodalso prepares compressed air with an oxygen content less than an amountnecessary to support combustion of hydrocarbons present in the wellbore. The cement composition is foamed with the reduced oxygen contentcompressed air and placed into the subterranean zone. Followingplacement of the foamed cement, the cement is allowed to set.

In another embodiment the current invention provides an improved methodof cementing a well bore penetrating a hydrocarbon producingsubterranean zone. The improved method comprises the steps of preparinga cement composition comprising hydraulic cement, sufficient water toform a slurry, and a mixture of foaming and foam stabilizing surfactantspresent in an amount sufficient to facilitate the formation andstabilization of foam. The improved method also prepares compressed airwith an oxygen content less than an amount necessary to supportcombustion of hydrocarbons by contacting the air with an oxygenscavenger prior to or after compressing the air. Accordingly, the orderof compressing the air and contacting the air with an oxygen scavengeris not critical to the current invention and may be reversed such thatthe oxygen content is lowered by contact with an oxygen scavenger priorto or after compressing the air. The cement composition is foamed withthe reduced oxygen content compressed air and placed into thesubterranean zone. Following placement of the foamed cement, the cementis allowed to set into a solid mass.

The current invention also provides an improved foamed cementcomposition comprising a hydraulic cement, water, and air having anoxygen content less than an amount required to support combustion ofhydrocarbons. Typically the water is present in an amount sufficient toform a slurry of the hydraulic cement. Additionally, the foamed cementcomposition normally comprises from about 20% to about 80% reducedoxygen content air by volume.

In yet another embodiment, the current invention provides a foamedcement composition comprising a hydraulic cement, water; and, air havingan oxygen content less than about 12.5% by volume. Typically the wateris present in an amount sufficient to form a slurry of the hydrauliccement. Additionally, the foamed cement composition normally comprisesfrom about 20% to about 80% reduced oxygen content air by volume.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 1. Method of Preparing aReduced Oxygen Content Foamed Cement

One aspect of the current invention provides a method for preparing animproved foamed cement. The steps necessary to prepare a foamed cementare generally well known to those skilled in the art as demonstrated byU.S. Pat. Nos. 6,500,252, 6,227,294, and 6,063,738 all of which areincorporated herein by reference.

The method of the current invention utilizes air with a reduced oxygencontent as the gas phase. In the method of the current invention, acement is prepared according to standard industry procedures. The cementslurry is then foamed using air with an oxygen content lower than thatnecessary to support combustion of hydrocarbons. Preferably, the oxygencontent is less than about 12.5% oxygen. More preferably, the oxygencontent is less than about 5% oxygen by volume. The resulting foamedcement is particularly suitable for carrying out primary cementingoperations in wells as a result of the cement compositions beinglightweight, having low fluid loss, being compressible during theslurry's transition time, and having good thermal insulation properties.

The method of preparing air with lowered oxygen content comprises thesteps of contacting the air with an oxygen scavenger and compressing theair with a conventional compressor. In one embodiment, the air contactsor passes through an oxygen scavenger such as sodium thiosulfateavailable from Calabrian Corp. of Houston, Tex. Other compounds suitablefor removing oxygen from air include as sodium sulfite, sodiumbi-sulfite, pyrogallic acid, pyrogallol, catechal, sodium erthythrobate,ascorbic acid, amines, resorcinol, quinones, and hydroquinones. As theair contacts the oxygen scavenger, the compound(s) contained therein,absorb or adsorb oxygen from the air. Following oxygen reduction, theair has an oxygen content of less than about 12.5% by volume,preferably, the oxygen content is less than about 5% by volume.Following oxygen reduction the air is compressed using a conventionalair compressor. Typically, the compressed air leaves the compressor at apressure in the range of about 100 KPa to about 14 MPa.

The order of compressing and reducing the oxygen content of the air isnot critical to the current invention. Thus, it is within the scope ofthe current invention to first compress the air and then contact thecompressed air with an oxygen scavenger. Either method of preparing thereduced oxygen content compressed air should perform satisfactorily inthe current invention.

A variety of hydraulic cements can be utilized in accordance with thepresent invention including those comprised of calcium, aluminum,silicon, oxygen, and/or sulfur which set and harden by reaction withwater. Such hydraulic cements include Portland cements, pozzolaniccements, gypsum cements, high alumina cements, and silica cements.Portland cements or their equivalents are generally preferred for use inaccordance with the present invention when performing cementingoperations in subterranean zones penetrated by well bores. Portlandcements of the types defined and described in API Specification ForMaterials And Testing For Well Cements, API Specification 10, 5^(th)Edition, dated Jul. 1, 1990 of the American Petroleum Institute areparticularly suitable. Preferred API Portland cements include classes A,B, C, G and H, with API classes A, G and H being more preferred, andclasses G and H being the most preferred.

The water utilized to form the foamed cement compositions of thisinvention can be fresh water or salt water. The term “salt water” isused herein to mean unsaturated salt solutions and saturated saltsolutions including brines and seawater. The water is included in thefoamed cement compositions in an amount sufficient to slurry thehydraulic cement. Generally, the water is present in the foamed cementcompositions in an amount in the range of from about 30% to about 60% byweight of hydraulic cement therein.

The gas utilized for foaming the cement slurry is the reduced oxygencontent air described above. The gas is present in an amount sufficientto foam the slurry, generally in an amount in the range of from about20% to about 80% by volume of the slurry.

Those skilled in the art are familiar with foaming and foam stabilizingsurfactants suitable for use in the downhole environment. A preferredmixture of such surfactants is described in U.S. Pat. No. 5,897,699issued to Chatterji et al. on Apr. 27, 1999, incorporated herein byreference. The patent discloses an aqueous solution of a mixture of analpha-olefinic sulfonate and a cocoylamidopropyl betaine.

Another preferred foaming and foam stabilizing surfactant mixture foruse in accordance with the present invention is comprised of anethoxylated alcohol ether sulfate of the formulaH(CH₂)_(a)(OC₂H₄)_(b)OSO₃NH₄ ⁺ wherein “a” is an integer in the range offrom about 6 to about 10 and “b” is an integer in the range of fromabout 3 to about 10, an alkyl or alkene amidopropylbetaine having theformula R′—CONHCH₂CH₂CH₂N⁺(CH₃)₂CH₂CO₂ ⁻ wherein R is a radical selectedfrom the group of decyl, cocoyl, lauryl, cetyl and oleyl and an alkyl oralkene amidopropyldimethylamineoxide. having the formulaR′—CONHCH₂CH₂CH₂N⁺(CH₃)₂O⁻ wherein R′ is a radical selected from thegroup of decyl, cocoyl, lauryl, cetyl and oleyl.

The ethoxylated alcohol ether sulfate is generally present in theabove-described mixture in an amount in the range of from about 60 toabout 64 parts by weight. The alkyl or alkene amidopropylbetaine isgenerally present in the mixture in an amount in the range of from about30 to about 33 parts by weight and the alkyl or alkeneamidopropyldimethylamineoxide is generally present in the additive in anamount in the range of from about 3 to about 10 parts by weight.

The most preferred foaming and foam stabilizing surfactant mixture ofthe type described above for use in accordance with this invention iscomprised of an ethoxylated alcohol ether sulfate wherein “a” in theformula set forth above is an integer in the range of from about 6 toabout 10 and the ethoxylated alcohol ether sulfate is present in thesurfactant mixture in an amount of about 63.3 parts by weight; the alkylor alkene amidopropyl-betaine is cocoylamidopropylbetaine and is presentin the mixture in an amount of about 31.7 parts by weight and the alkylor alkene amidopropyldimethylamineoxide iscocoylamidopropyldimethylamineoxide and is present in an amount of about5 parts by weight.

The foaming and foam stabilizing surfactant mixture is generallyincluded in the foamed cement composition of this invention in an amountin the range of from about 0.5% to about 5% by volume of water in thecement slurry, preferably in an amount of from about 1% to about 2.5%.

As will be understood by those skilled in the art, the foamed wellcement compositions of this invention can include a variety ofconventional additives for improving or changing the properties of thefoamed cement compositions. Examples of such additives include, but arenot limited to, set retarding agents, fluid loss control agents, setaccelerating agents and formation conditioning agents.

Set retarding agents are included in the foamed cement compositions whenit is necessary to extend the time in which the foamed cementcompositions can be pumped so that they will not set prior to beingplaced at a desired location in a well. Examples of set retarding agentswhich can be used include, but are not limited to, lignosulfonates suchas calcium and sodium lignosulfonate, organic acids such as tartaricacid and gluconic acid, copolymers of acrylic acid, maleic acid andothers. The proper amount of set retarding agent required for particularconditions can be determined by conducting a “thickening time test” forthe particular retarder and foamed cement composition. Such tests aredescribed in the API Recommend Practice 10B mentioned above. A suitableset retarder for use in accordance with the present invention is acopolymer or copolymer salt of 2-acrylamido-2-methylpropane sulfonicacid and acrylic acid. The copolymer comprises from about 60 to about 90mole percent 2-acrylamido-2-methylpropane sulfonic acid with the balancecomprising acrylic acid, and the copolymer or salt thereof preferablyhas an average molecular weight below about 5,000. The most preferredretardant is described in U.S. Pat. No. 6,227,294, which is incorporatedherein by reference. When used, a set retarder is included in the foamedcement compositions of this invention in amounts ranging from about 0.1%to about 2% by weight of hydraulic cement in the compositions.

Examples of suitable set accelerating agents include, but are notlimited to, calcium chloride, zinc formate and triethanolamine, andexamples of formation conditioning agents include, but are not limitedto, potassium chloride and sodium chloride.

The foamed cement slurries of this invention may be prepared inaccordance with any of the mixing techniques utilized in the art. In onepreferred method, a quantity of water is introduced into a cementblender followed by the hydraulic cement utilized. A preferred cementcomposition suitable for foaming comprises Portland cement and a mixtureof foaming and foam stabilizing surfactants. The mixture of foaming andfoam stabilizing surfactants being present in the cement composition inan amount ranging from about 1% to about 5% by volume of the water inthe composition. The mixture is agitated for a sufficient period of timeto form a pumpable non-foamed slurry. Other liquid additives utilized,if any, are preferably added to the water prior to when the hydrauliccement is mixed therewith and other dry solids, if any, are normallyadded to the water and cement prior to mixing.

Following formation of the non-foamed slurry, the reduced oxygen contentair is injected into the slurry to form a foamed cement. As previouslynoted, the injected air should have an oxygen content of about 12.5% byvolume or less. Preferably, the oxygen content is less than about 5% byvolume.

2. Method of Cementing With a Reduced Oxygen Content Cement

Cementing operations are carried out in oil and gas wells for a varietyof reasons. The most common operations are performed to secure a casingwithin the well bore and to isolate non-producing or water producingzones from hydrocarbon producing zones. As noted above, cementingprocesses using foamed cement require additional steps to precludecoalescence of the gas cells within the foamed cement.

When using foamed cement for the primary cementing operation, thewellhead is preferably equipped with an annular pressure-containingdevice. If a pressure-containing device is unavailable, then an unfoamedcement cap is injected ahead of the foamed cement. The unfoamed capinterval should be tailored for each specific job. Typically, a 200-footinterval is considered the minimum length for the unfoamed cap.

Prior to the current invention, oxygen-containing gases such as air werenot suitable for foaming a cement. Due to the presence of hydrocarbonswithin the well bore, the introduction of air into the wellbore wouldlikely create a combustible gas in the well bore. In general, thepossibility of an explosion exists when natural gas and otherhydrocarbons associated with petroleum are exposed to an oxygenconcentration of greater than about 12.5% by volume. The concentrationof oxygen necessary to support combustion will decrease as temperatureand pressure increases. Additionally, once the oxygen/hydrocarbonmixture reaches critical mass, the chance of an explosion increasesexponentially with increasing pressure. Therefore, to reduce the risk ofan uncontrolled downhole explosion, current foaming operations aretypically performed with nitrogen. However, as mentioned above, nitrogeninjection requires the use of equipment not commonly found at the wellbore site.

Accordingly, the current invention provides an improved cementing methodwherein foaming operations are carried out by injection of reducedoxygen content air into the desired cement composition. The method ofpreparing air with lowered oxygen content comprises the steps ofcontacting the air with an oxygen scavenger and compressing the air witha conventional compressor. In one embodiment, the air contacts or passesthrough an oxygen scavenger such as sodium thiosulfate available fromCalabrian Corp. of Houston, Tex. Other compounds suitable for removingoxygen from air include as sodium sulfite, sodium bi-sulfite, pyrogallicacid, pyrogallol, catechal, sodium erthythrobate, ascorbic acid, amines,resorcinol, quinones, and hydroquinones. As the air contacts the oxygenscavenger, the compound(s) contained therein, absorb or adsorb oxygenfrom the air. After contacting the oxygen scavenger, the oxygen contentof the air has been lowered sufficiently to preclude combustion ofhydrocarbons found in the well bore. Preferably, the oxygen content isless than about 12.5% by volume. More preferably, the oxygen content isless than about 5% by volume. As noted above, lowering the oxygenconcentration to about 12.5% or less by volume will reducing thelikelihood of an uncontrolled explosion in the downhole environment.Following oxygen reduction the air is compressed using a conventionalair compressor. Typically, the compressed air leaves the compressor at apressure in the range of about 100 KPa to about 14 MPa.

As indicated above, the order of compressing and reducing the oxygencontent of the air is not critical to the current invention. Thus, it iswithin the scope of the current invention to first compress the air andthen contact the compressed air with an oxygen scavenger. Either methodof preparing the reduced oxygen content compressed air should performsatisfactorily in the current invention.

As known to those skilled in the art, oxygen scavengers are compoundscapable of absorbing or adsorbing oxygen from air. For example, SPEpaper number 28978, “Effects of Oxygen on Fracturing Fluids,” by Walkeret al., 1995, demonstrates that one mole of sodium thiosulfate iscapable of consuming 2 moles of oxygen. Likewise a mole of sodiumsulfite is will consume one mole of oxygen. Other commonly used oxygenscavenging compounds include sodium thiosulfate, sodium sulfite, sodiumbi-sulfite, pyrogallic acid, pyrogallol, catechal, sodium erthythrobate,ascorbic acid, amines, resorcinol, quinones and hydroquinones. Apreferred compound is sodium thiosulfate available from Calabrian Corp.of Houston, Tex.

Following preparation of the reduced oxygen content compressed air, theair is injected into the cement, according to standard operatingprocedures known to those skilled in the art, at a rate sufficient toproduce a foamed cement. One preferred method of cementing with reducedoxygen content foamed cement comprises the steps of: (a) preparing anon-foamed cement slurry comprised of Portland cement, sufficient waterto produce a slurry and a mixture of foaming and foam stabilizingsurfactants, the mixture being present in the cement composition in anamount ranging from about 1% to about 5% by volume of the water in thecomposition; (b) preparing reduced oxygen content compressed air havingan oxygen content in the compressed air of less than about 12.5% byvolume or less; (c) foaming the cement composition by injecting thereduced oxygen air into the cement composition; (d) placing theresulting foamed cement at the desired downhole location; and, (e)allowing the foamed cement composition to set into a solid mass therein.Other liquid additives utilized, if any, are preferably added to thewater prior to when the hydraulic cement is mixed therewith and otherdry solids, if any, are normally added to the water and cement prior tomixing.

3. Foamed Cement Composition Containing Reduced Oxygen Content Air

The current invention also provides a novel foamed cement composition.The foamed cement composition of the current invention eliminates theneed for liquid nitrogen storage or other cryogenic equipment productionat the well bore. Briefly stated, the foamed cement composition of thecurrent invention comprises hydraulic cement, sufficient water toproduce a slurry, a mixture of foaming and foam stabilizing surfactantsand sufficient reduced oxygen content air to foam the slurry.Additionally, as known to those skilled in the art other performanceenhancing additives such as, but not limited to, set retarding agents,fluid loss control agents, set accelerating agents and formationconditioning agents may be included in the foamed cement composition.

Preferred cements include Portland cements, pozzolan cements, gypsumcements, high alumina content cements, silica cements and highalkalinity cements. Portland cements or their equivalents are generallypreferred for use in accordance with the present invention whenperforming cementing operations in subterranean zones penetrated by wellbores. Portland cements of the types defined and described in APISpecification For Materials And Testing For Well Cements, APISpecification 10, 5^(th) Edition, dated Jul. 1, 1990 of the AmericanPetroleum Institute are particularly suitable. Preferred API Portlandcements include classes A, B, C, G and H, with API classes A, G and Hbeing more preferred, and class G and H being the most preferred.

The water in the foamed cement composition may be fresh water or saltwater, as defined above. Preferably, the concentration of water in thefoamed cement is in the range of about 30% to about 60% by weight of thehydraulic cement therein.

The gas contained within the foamed cement is reduced oxygen contentair. Typically, from about 20% to about 80% of the volume of the foamedcement is the reduced oxygen content air. Preferably, from about 20% toabout 60% by volume of the foamed cement is the reduced oxygen contentair.

Finally, the foaming and foam stabilizing surfactant mixture found inthe foamed cement composition generally corresponds to about 0.5% toabout 5% by volume of the water found in the cement slurry. Morepreferably the foaming and foam stabilizing surfactant mixture in thefoamed cement composition corresponds to about 1% to about 2.5% byvolume of the water found in the cement slurry.

Thus, a particularly preferred foamed cement composition which uponsetting has high strength, resiliency, ductility and toughness iscomprised of Portland cement, a mixture of foaming and foam stabilizingsurfactants, the mixture being present in the cement composition in anamount ranging from about 0.5% to about 5% by volume of the water in thecomposition, and sufficient water to slurry the cement. Additionally,the preferred foamed cement composition comprises sufficient reducedoxygen content air to foam the slurry. At a minimum, the reduced oxygencontent air has an oxygen content lower than an amount necessary tosupport combustion of hydrocarbons. Preferably, the reduced oxygencontent compressed air has less than about 12.5% oxygen by volume. Morepreferably the reduced oxygen content air contains less than about 5%oxygen by volume. Preferably, the foamed cement composition willcomprise from about 20% to about 60% by volume reduced oxygen contentair.

Other embodiments of the current invention will be apparent to thoseskilled in the art from a consideration of this specification orpractice of the invention disclosed herein. However, the foregoingspecification is considered merely exemplary of the current inventionwith the true scope and spirit of the invention being indicated by thefollowing claims.

What is claimed is:
 1. A method of foaming cement comprising the stepsof: preparing a cement composition comprising hydraulic cement,sufficient water to form a slurry, and a mixture of foaming and foamstabilizing surfactants; preparing compressed air with an oxygen contentless than an amount necessary to support combustion of hydrocarbons; andfoaming the cement composition with the reduced oxygen contentcompressed air.
 2. The method of claim 1 wherein the compressed air hasless than about 12.5% oxygen content by volume.
 3. The method of claim 1wherein the compressed air has less than about 5% oxygen content byvolume.
 4. The method of claim 1 wherein the step of preparing thecompressed air comprises contacting the air with an oxygen scavengerprior to or after compressing the air.
 5. The method of claim 4 whereinthe oxygen scavenger is selected from the group consisting of sodiumthiosulfate, sodium sulfite, sodium bi-sulfite, pyrogallic acid,pyrogallol, catechal, sodium erthythrobate, ascorbic acid, amines,resorcinol, quinones and hydroquinones and mixtures thereof.
 6. Themethod of claim 1 wherein the foamed cement composition comprises fromabout 20% to about 80% reduced oxygen content air by volume.
 7. Themethod of claim 1 wherein the foamed cement composition comprises fromabout 20% to about 60% reduced oxygen content air by volume.
 8. Themethod of claim 1 wherein the mixture of foaming and foam stabilizationsurfactants is present in the cement composition in the range of fromabout 0.5% to about 5% by volume of water in the cement slurry.
 9. Themethod of claim 1 wherein the mixture of foaming and foam stabilizationsurfactants is present in the cement composition in the range of fromabout 1% to about 2.5% by volume of water in the cement slurry.
 10. Themethod of claim 1 wherein the mixture of foaming and foam stabilizationsurfactants comprises an alpha-olefinic sulfonate and acocoylamidopropyl betaine.
 11. The method of claim 1 wherein the mixtureof foaming and foam stabilization surfactants comprises an ethoxylatedalcohol ether sulfate of the formula H(CH₂)_(a)(OC₂H₄)_(b)OSO₃NH₄ ⁺wherein “a” is an integer in the range of from about 6 to about 10 and“b” is an integer in the range of from about 3 to about 10, an alkyl oralkene amidopropylbetaine having the formulaR′—CONHCH₂CH₂CH₂N⁺(CH₃)₂CH₂CO₂ ⁻ wherein R is a radical selected fromthe group consisting of decyl, cocoyl, lauryl, cetyl and oleyl and analkyl or alkene amidopropyldimethylamineoxide having the formulaR′—CONHCH₂CH₂CH₂N⁺(CH₃)₂O⁻ wherein R′ is a radical selected from thegroup consisting of decyl, cocoyl, lauryl, cetyl and oleyl.
 12. Themethod of claim 11 wherein the ethoxylated alcohol ether sulfate ispresent in an amount ranging from about 60 to about 64 parts by weight,the alkyl or alkene amidopropylbetaine is present in an amount rangingfrom about 30 to about 33 parts by weight and the alkyl or alkeneamidopropyldimethylamineoxide is present in an amount ranging from about3 to about 10 parts by weight of the mixture of foaming and foamstabilization surfactants.
 13. The method of claim 1 wherein thehydraulic cement is selected from the group consisting of Portlandcements, pozzolanic cements, gypsum cements, high alumina cements, andsilica cements.
 14. The method of claim 1 wherein the hydraulic cementis selected from the group consisting of API Portland cements classes A,B, C, G and H.
 15. A method of foaming cement comprising the steps of:preparing a cement composition comprising hydraulic cement, sufficientwater to form a slurry, and a mixture of foaming and foam stabilizingsurfactants present in an amount sufficient to facilitate the formationand stabilization of foam; preparing compressed air with an oxygencontent less than about 12.5% oxygen content by volume contacting theair with an oxygen scavenger prior to or after compressing the air; andfoaming the cement composition with the reduced oxygen contentcompressed air.
 16. The method of claim 15 wherein the compressed airhas less than 5% oxygen content by volume.
 17. The method of claim 15wherein the oxygen scavenger is selected from the group consisting ofsodium thiosulfate, sodium sulfite, sodium bi-sulfite, pyrogallic acid,pyrogallol, catechal, sodium erthythrobate, ascorbic acid, amines,resorcinol, quinones and hydroquinones and mixtures thereof.
 18. Themethod of claim 15 wherein the foamed cement composition comprises fromabout 20% to about 80% reduced oxygen content air by volume.
 19. Themethod of claim 15 wherein the foamed cement composition comprises fromabout 20% to about 60% reduced oxygen content air by volume.
 20. Amethod of cementing in a subterranean zone comprising the steps of:preparing a cement composition comprising hydraulic cement, sufficientwater to form a slurry, and a mixture of foaming and foam stabilizingsurfactants; preparing compressed air with an oxygen content less thanan amount necessary to support combustion of hydrocarbons present in thesubterranean zone; foaming the cement composition with the reducedoxygen content compressed air; placing the resulting foamed cementcomposition into the subterranean zone; and allowing the foamed cementcomposition to set therein.
 21. The method of claim 20 wherein thecompressed air has less than about 12.5% oxygen content by volume. 22.The method of claim 20 wherein the compressed air has less than about 5%oxygen content by volume.
 23. The method of claim 20 wherein the step ofpreparing the compressed air comprises contacting the air with an oxygenscavenger prior to or after compressing the air.
 24. The method of claim23 wherein the oxygen scavenger is selected from the group consisting ofsodium thiosulfate, sodium sulfite, sodium bi-sulfite, pyrogallic acid,pyrogallol, catechal, sodium erthythrobate, ascorbic acid, amines,resorcinol, quinones and hydroquinones and mixtures thereof.
 25. Themethod of claim 20 wherein the foamed cement composition comprises fromabout 20% to about 80% reduced oxygen content air by volume.
 26. Themethod of claim 20 wherein the foamed cement composition comprises fromabout 20% to about 60% reduced oxygen content air by volume.
 27. Themethod of claim 20 wherein the mixture of foaming and foam stabilizationsurfactants is present in the cement composition in the range of fromabout 0.5% to about 5% by volume of water in the cement slurry.
 28. Themethod of claim 20 wherein the mixture of foaming and foam stabilizationsurfactants is present in the cement composition in the range of fromabout 1% to about 2.5% by volume of water in the cement slurry.
 29. Themethod of claim 20 wherein the mixture of foaming and foam stabilizationsurfactants comprises an alpha-olefinic sulfonate and acocoylamidopropyl betaine.
 30. The method of claim 20 wherein themixture of foaming and foam stabilization surfactants comprises anethoxylated alcohol ether sulfate of the formulaH(CH₂)_(a)(OC₂H₄)_(b)OSO₃NH₄ ⁺ wherein “a” is an integer in the range offrom about 6 to about 10 and “b” is an integer in the range of fromabout 3 to about 10, an alkyl or alkene amidopropylbetaine having theformula R—CONHCH₂CH₂CH₂N⁺(CH₃)₂CH₂CO₂ ⁻ wherein R is a radical selectedfrom the group consisting of decyl, cocoyl, lauryl, cetyl and oleyl andan alkyl or alkene amidopropyldimethylamineoxide having the formulaR′—CONHCH₂CH₂CH₂N⁺(CH₃)₂O⁻ wherein R′ is a radical selected from thegroup consisting of decyl, cocoyl, lauryl, cetyl and oleyl.
 31. Themethod of claim 30 wherein the ethoxylated alcohol ether sulfate ispresent in an amount ranging from about 60 to about 64 parts by weight,the alkyl or alkene amidopropylbetaine is present in an amount rangingfrom about 30 to about 33 parts by weight and the alkyl or alkeneamidopropyldimethylamineoxide is present in an amount ranging from about3 to about 10 parts by weight of the mixture of foaming and foamstabilization surfactants.
 32. The method of claim 30 wherein thehydraulic cement is selected from the group consisting of Portlandcements, pozzolanic cements, gypsum cements, high alumina cements, andsilica cements.
 33. The method of claim 30 wherein the hydraulic cementis selected from the group consisting of API Portland cements classes A,B, C, G and H.
 34. A method of cementing in a subterranean zonecomprising the steps of: preparing a cement composition comprisinghydraulic cement, sufficient water to form a slurry, and a mixture offoaming and foam stabilizing surfactants present in an amount sufficientto facilitate the formation and stabilization of foam; preparingcompressed air with an oxygen content less than about 12.5% oxygencontent by volume by contacting the air with an oxygen scavenger priorto or after compressing the air; foaming the cement composition with thereduced oxygen content compressed air; placing the resulting foamedcement composition into the subterranean zone; and allowing the foamedcement composition to set therein.
 35. The method of claim 34 whereinthe compressed air has less than 5% oxygen content by volume.
 36. Themethod of claim 34 wherein the oxygen scavenger is selected from thegroup consisting of sodium thiosulfate, sodium sulfite, sodiumbi-sulfite, pyrogallic acid, pyrogallol, catechal, sodium erthythrobate,ascorbic acid, amines, resorcinol, quinones and hydroquinones andmixtures thereof.
 37. The method of claim 34 wherein the foamed cementcomposition comprises from about 20% to about 80% reduced oxygen contentair by volume.
 38. The method of claim 34 wherein the foamed cementcomposition comprises from about 20% to about 60% reduced oxygen contentair by volume.
 39. A foamed cement comprising: a hydraulic cement;water; and air having an oxygen content less than an amount required tosupport combustion of hydrocarbons.
 40. The composition of claim 39wherein the air has less than 12.5% oxygen content by volume.
 41. Thecomposition of claim 39 wherein the air has less than 5% oxygen contentby volume.
 42. The composition of claim 39 wherein the water is freshwater or salt water and the water comprises from about 30% to about 60%by weight of hydraulic cement.
 43. The composition of claim 39 whereinthe hydraulic cement is selected from the group consisting of Portlandcements, pozzolanic cements, gypsum cements, high alumina cements, andsilica cements.
 44. The composition of claim 39 wherein the hydrauliccement is selected from the group consisting of API Portland cementsclasses A, B, C, G and H.
 45. The composition of claim 39 wherein thefoamed cement composition comprises from about 20% to about 80% reducedoxygen content air by volume.
 46. The composition of claim 39 whereinthe foamed cement composition comprises from about 20% to about 60%reduced oxygen content air by volume.
 47. The composition of claim 39further comprising a mixture of foaming and foam stabilizing surfactantsin an amount sufficient to facilitate formation and stabilization offoam.
 48. The composition of claim 39 wherein the mixture of foaming andfoam stabilizing surfactants comprises an alpha-olefinic sulfonate and acocoylamidopropyl betaine.
 49. The composition of claim 39 wherein themixture of foaming and foam stabilizing surfactants comprises anethoxylated alcohol ether sulfate of the formulaH(CH₂)_(a)(OC₂H₄)_(b)OSO₃NH₄ ⁺ wherein “a” is an integer in the range offrom about 6 to about 10 and “b” is an integer in the range of fromabout 3 to about 10, an alkyl or alkene amidopropylbetaine having theformula R—CONHCH₂CH₂CH₂N⁺(CH₃)₂CH₂CO₂ ⁻ wherein R is a radical selectedfrom the group consisting of decyl, cocoyl, lauryl, cetyl and oleyl andan alkyl or alkene amidopropyldimethylamineoxide having the formulaR′—CONHCH₂CH₂CH₂N⁺(CH₃)₂O⁻ wherein R′ is a radical selected from thegroup consisting of decyl, cocoyl, lauryl, cetyl and oleyl.
 50. Thecomposition of claim 49 wherein the ethoxylated alcohol ether sulfate ispresent in an amount ranging from about 60 to about 64 parts by weight,the alkyl or alkene amidopropylbetaine is present in an amount rangingfrom about 30 to about 33 parts by weight and the alkyl or alkeneamidopropyldimethylamineoxide is present in an amount ranging from about3 to about 10 parts by weight of the mixture of foaming and foamstabilization surfactants.
 51. The composition of claim 47 wherein themixture of foaming and foam stabilizing surfactants comprises from about0.5% to about 5% by volume of the water present in the composition. 52.The composition of claim 47 wherein the mixture of foaming and foamstabilizing surfactants comprises from about 1% to about 2.5% by volumeof the water present in the composition.
 53. A foamed cement comprising:a hydraulic cement; water; and air having an oxygen content less thanabout 12.5% by volume.
 54. The composition of claim 53 wherein the airhas less than about 5% oxygen content by volume.
 55. The composition ofclaim 53 wherein the water is fresh water or salt water and the watercomprises from about 30% to about 60% by weight of hydraulic cement. 56.The composition of claim 53 wherein the hydraulic cement is selectedfrom the group consisting of Portland cements, pozzolanic cements,gypsum cements, high alumina cements, and silica cements.
 57. Thecomposition of claim 53 wherein the hydraulic cement is selected fromthe group consisting of API Portland cements classes A, B, C, G and H.58. The composition of claim 53 further comprising a mixture of foamingand foam stabilizing surfactants in an amount sufficient to facilitateformation and stabilization of foam.
 59. The composition of claim 58wherein the mixture of foaming and foam stabilizing surfactantscomprises from about 1% to about 2.5% by volume of the water present inthe composition.
 60. The composition of claim 53 wherein the foamedcement composition comprises from about 20% to about 60% reduced oxygencontent air by volume.